Two civilians were killed in the initial bombing by the Kurdistan Workers' Party (PKK) in the town of Cinar and three more lost their lives when a building collapsed due to damage caused by the blast, the governor's office of Diyarbakir province said in a statement.

The late-night blast in Cinar caused huge damage to the residential building used by the police officers and their families, with the entire outer wall blown out, an AFP correspondent said.

The governor's office said 14 people were injured in the initial bomb blast while 25 were wounded in the building collapse, including five who had been rescued from the rubble by emergency teams.

The attackers also followed up the car bomb attack with rocket fire and long-range gunfire, reports said.

The Dogan news agency said a 40-minute clash then ensued between security forces and the rebels.

Security forces have now blocked all entrances and exits to Cinar and have launched an operation to find the assailants, it added.

"We were about to go to bed when we heard a huge blast," said Cinar resident Sitki Dinc, who lives a few metres away from the police station.

"I thought it was an atomic bomb. It threw me to the ground. Then I heard gunfire and I took my children downstairs (to the basement). We stayed there until we didn't hear anything outside anymore."

The PKK launched an insurgency against the Turkish state in 1984, initially fighting for Kurdish independence although it now presses more for greater autonomy and rights for the country's largest ethnic minority.

The conflict has left tens of thousands of people dead.

A woman places flowers at the site of Tuesday's suicide bomb attack at Sultanahmet square in Istanbul, Turkey
Thomson Reuters

A new upsurge of violence between the security forces and the PKK erupted in July following attacks blamed on Islamic extremists, shattering a fragile two-and-a-half-year truce.

Vowing to flush out the PKK from Turkey's urban centres, the authorities have in recent weeks enforced curfews in three locations in the southeast to back up military operations that activists say have killed dozens of civilians.

A curfew has been in force in the Sur neighbourhood of Diyarbakir city since December 2 while curfews in the towns of Silopi and Cizre in Sirnak province have been in place since December 14.

According to a report published Wednesday by the Diyarbakir branch of the Human Rights Association (IHD), 170 civilians have been killed under military curfews imposed in seven towns and cities in the southeast from August 16.

In Diyarbakir alone, 37 civilians had been killed, including 10 children and three women, it said. The government says hundreds of "terrorists" have been killed but denies the civilian losses are on this scale.

Kurdish fighters gesture while carrying their parties' flags in Tel Abyad of Raqqa governorate after they said they took control of the area June 15, 2015.
REUTERS/Rodi Said

Kurdish militias are fighting IS militants in northern Syria with American support and the PKK itself has clashed with the jihadists around its strongholds in northern Iraq.

But President Recep Tayyip Erdogan said after the Istanbul attack that the government makes no differentiation between "terror" groups "whatever their name or abbreviation is".

Erdogan also lashed out at Turkish and foreign academics -- including the renowned social activist and linguist Noam Chomsky -- as being "ignorant" for signing a petition calling for an end to the security operations in the southeast.

In other violence blamed on the PKK overnight, militants launched a rocket and gun attack on a gendarmerie post in Midyat in Mardin province, Dogan said. There were no reports of casualties.

Dogan also said a policeman was shot dead in a district of the capital Ankara, but there was no indication of any link to the PKK.